Cognitive neuroscience Flashcards
what is cognitive neuroscience
the study of the mind
what is mind/ what is reality
dualism
mind and body are different
separate entities
penal gland
centre of the brain
close to ventricles
impulses would be sent to and form ventricles from body
what is the mind
- Collection of abilities to survive and thrive
- Decision making
- Consciousness
- Resasoning
- Memory
- Attention
- Cognition
- Emotionc
- Feelings
- Perception
phrenology
mental abilities are processed by completely separate brain areas
franz Joseph gall
phrenology
distinctive cranial and facial features - bumps / shape of the skull = different mental abilities - different sizes of subsections of the brain - different skills
what do we know now
not completely separate brain areas - interact with each other - no such thing as area that’s dedicated to one thing
different nodes are important for any different mental abilities
brocas area
speech
wernickes area
language comprehension
Pavlovs dog
- He first used a unconditioned / natural response
- Food = elicits salivation
- Then … compare with neutral stimulus ( sound) = no response
- Then pair stimuli together = neutral and unconditioned stimulus
- Then neural stimulus turns to conditioned stimuli
sound = elicits salivation
psychophysics
measurement of physical stimuli on the mind
absolute threshold
smallest stimulus energy that can be perceived
just noticeable difference
smallest change in stimulus energy that can be perceives
webes law
the change in stimulus intensity that can just be noticed is a constant fraction of the stimulus intensity
applies to many stimuli and modalities (light brightness, sound intensity)
change in stimulus intensity / stimulus intensity = K
temporal resolution
measure individual action potentials
spatial resolution
know which neuron we are recording from
types of excitation and inhibition
- Feedforward excitation
- Feedforward inhibition
- Feedback inhibition
- Inhibitory neuroscience
- Lateral inhibition
Mutual inhibition
neural activity
locally and between brain areas
changing every moment
giving rise to circuits that account for our perception
decisions and actions
correlation vs causation
not always equal
confounding factors
how does MRI work
- atoms spin in random directions -like tops - around their individual magnetic fields
- in magnetic field produced by MRI - atoms line up either north or south - about half the atoms of each way - few unmatched atoms
- when ratio frequency pulse is applied - unmatched atoms spin the other way
- when the radio frequency is turned off extra atoms return to normal position emitting energy
- the energy sends a signal to a computer - computer uses a mathematical formula to convert the signal to an image
what is the physiological bases of fMRI
There is an oversupply of oxyhaemaglobin to an active brain area
The blood oxygen level dependent response
stimulus
1. neuronal activity (excitatory activity and inhibitory activity, anaesthetic influence)
2. neuromuscular coupling (metabolic signal unknown, anaesthetic influence)
3. haemodynamic response ( blood flow, blood oxygenation level, blood volume, haemltocrit)
4. detection by MRI scanner ( magnetic field strength, TR, repetition time, TE echo time, spin or gradient echo)
BOLD signal
correlates more with the local field potentials (LFPs entry of synaptic information to a particular region) than with the single, multi unit activity (AP generated in that area) but this is a very delayed response
experimental design in fMRI
block design
slow event related design
fast event related design
hybrid event related design
fMRI in schizophrenic patients
Altered functional responses during a working memory task in the prefrontal cortex
blue = hypo activation
orange = hyperactivation
active brain area =
more oxygen
advantages of fMRI
hyper activation
non invasive
no exogenous ligand
poor temporal resolution
EEG - electroencephalogram
activity of thousands of neurones beneath each electrode
cover whole scalp
resolution of EEG
spatial resolution is poor
temporal resolution is excellent
where does most of the signal come from in an EEG
most of the signal comes from the cortex
transcranial magnetic stimulation
TMS coil held above the head
magnetic field
electical current generated in the skull
depending on coil shape - generate different patterns of electrical activity
double coil cone - penetrate deeper - choice of coil important
different types of TMS
single pulse
repetitive stimulation
repetitive TMS protocols
<1Hz = decreases activity in an area
> 1Hz = increases activity in an area
theta burst - varied and prolonged effects depending on the stimulation sequence
motor evoked potentials
direct stimulation - pathway - threshold in disease
priming anticipation of movement increases tbs effect
temporary lesions
short term - single pulse disrupts 1-2 cm 2 region for up to 50ms
medium term - repetitive stimulation (5Hz for 10 s ) - longer lasting and wider ranging effects
offline TMS - intense stimuli - impair function for 45min
treatment for depression??
advantages and dis of TMS
very high temporal resolution
high spatial resolution
casual inferences
requires detailed hypothesis
